Albany today unplugged power generating companies’ shocking grab for $500 million of New Yorkers’ electric bill cash over the next year.

The state Senate sent to Gov. Cuomo a bill that writes into law property tax breaks the city promised to give generating companies. The bill passed the Assembly last week.

Cuomo and Mayor Bloomberg said that when it’s enacted, the bill will eliminate the rationale federal energy regulators cited in giving the generators their whopping rate boost, which was first reported by The Post in April.

If the boost is allowed to stand, city residents’ Con Ed bills will leap by up to 12 percent this summer.

“There is now zero justification for the massive rate increase,” Bloomberg said in a statement.

Cuomo said the state would immediately file papers with the Federal Energy Regulatory Commission to reverse its ruling imposing the rate hike.

Generating companies had argued to FERC that the city’s property tax break promise wasn’t solid enough for them to rely on in setting prices.

FERC bought their argument, and in January gave them permission to set their prices as if the tax breaks didn’t exist.

City and state officials contended FERC’s decision amounted to a windfall for generating companies that could add up to $1 billion or more over the next three years — all from New York City electric ratepayers.

“Passage of this bill gives FERC 100 percent of the evidence it needs to promptly reverse its wrongheaded decision,” said Sen. Charles Schumer (D-NY), who complained about the ruling in a phone call to FERC chairman Jon Wellinghoff.

It’s unclear when FERC will act on the city and state requests to roll back the rate hike. “We still have the petitions for review under consideration,” said FERC spokesman Craig Cano.